| ObjectiveIn order to observe the efficacy of microwave tissue coagulation (MTC) on tumors, we used SD-rats to establish the animal model of submandibular gland tumor. MTC was used on the animal model and the flow cytometer (FCM) was used to detect the tumor cells and to investigate the mechanism of the apoptosis induced by MTC and to evaluate the therapeutic efficacy of the MTC.Material and methodsPart one The establishment of SD-rats submandibular gland tumor:1. Eighty healthy SD-rats aged two weeks were divided into four groups. DMBA acetone solution (0.05ml) was injected into the submandibular gland. Group A was injected with 2% DMBA acetone solution one time, Group B with 4% DMBA acetone solution one time, Group C with 4% DMBA acetone solution repeated injection three times with two weeks interval and Group D with 4% DMBA acetone solution repeated injection three times with two weeks interval and the thymus was extirpated at the first time of injection. Equivalent dose of acetone solution was injected into the contrast gland. All the animals were fed with feedstuff, which contain 0.05% Phenobarbital one week later and continued for three months.2. A small portion of gland tissues was incised every week, and observed under the microscope until the tumor occurred tectologicaly.Part two Observation of MTC on submandibular gland tumor:1. When the animal model tumor exceeded 2cm in diameter, 45 rats were selected for the experiment.2. The antenna of microwave coagulation machine was put into the tumor. When the designed therapy finished, the tumor was cut along the antenna to observe the form of coagulation and to measure the coagulation area. If there are remains of uncoagulated tumor, MTC therapy was given once more to coagulate the whole tumor.3. Twenty-seven rats were treated with MTC therapy, 3 with operation, and 3 were used as blank contrast group. Based on the different power and time combination, the MTC group was divided into nine subgroups, including 30wx3m, 30w×5m, 30w×6m, 40w×3m, 40w×5m, 40w×6m, 60w×3m, 60wx5m, and 60wx6m subgroups. There were three rats in each subgroup.4. Observation of the tectology after MTC: 12 rats with 50wx4m were used to observe the histologic changes at the time of Oh, 24h, 2d, 7d, 15d, 30d after MTC.Part three The investigation of flow cytometer after MTC:1. Nine rats of the animal modal were used to evaluate the DNA changes after MTC by flow cytometer, which include the cell cycle and the rate of apoptotic cells. The rats were treated by MTC with 30w×3m(3), 30wx6m(3), and 60w×3m(3). A small portion of tumor tissues was incised at the time of Oh, 4h, 8h, 12h, 16h, 24h, 36h and 72h after MTC.ResultsPart one: A tumor mass occurred as early as five weeks after the first injection of DMBA, and the latest 16 weeks after the injection of DMBA. The rate of induced tumors in each group was as follows: Group A was 25% (5/20), Group B 30% (620), Group C 50% (1020), and Group D 70% (1420). The duration of tumor occurrent in each group was different: Group A 10-13w, Group B 9-14w, Group C 6-16w, and Group D 5-10w.Most of the tumors occurred in the duration of 7-10 weeks. The histological diagnosis was as follows: squamous carcinoma in 19 rats, fibrosarcoma 13, and adenocarcinoma 3. The histological changes were observed: atrophy of the alveolus and the remnant of the duct were seen in submandibular gland one week after the injection, as well as the infiltration of inflammatory cells. Squamous metaplasia occurred in the duct epithelium with local atypical hyperplasia four weeks after the injection. Squamous cell carcinoma occurred with the cells arrangement like the nests eight weeks after the injection.Part two1. An ellipse coagulation area with the axis along the antenna of the MTC was seen swiftly after MCT therapy. The average coagulation area for each group of 30w×3m, 30w×5m, 30w×6m, 40w×3m, 40w×5m, 40w×6m, 60w×3m, 60w×5m, and 60w×6m was 1.1×0.85cm2, 1.32×1.28cm2, 1.9×1.75cm2, 1.77×1.42cm2, 1.83×1.78cm2, 2.22×2.13cm2, 2.37×2.2cm2, 3.0×... |
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